Abstract—The static scale-inhibiting method was employed to

investigate the scale inhibition performance of

polyepoxysucci-nic acid (PESA) on calcium phosphate, and

molecular dynamics (MD) method was used to simulate the

interactions between PESA and (001), (010) surfaces of

hydroxyapatite (HAP, the most thermodynamically stable phase

of calcium phosphate) in aqueous solution. The results show that

the scale inhibition efficiency of PESA increases as the increase

in the concentration and PESA possesses better scale inhibition

performance compared with PAA while poor performance

compared with POCA. Moreover, PESA molecules adsorb on

the surfaces rather than remain in the bulk water in MD

simulations and the binding energy of PESA with (010) is

significantly stronger (1.8 times) than that with (001) surface,

which is mainly provided by hydrogen bonds and coulomb

interaction verified by the analysis of radial distribution

functions. The adsorption of PESA changes the growth rate of

crystal surfaces and leads to changes in the crystal morphology

of HAP, according well with the scanning electron microscopy

(SEM) results. These suggestions may be useful for the synthesis

of new, highly effective scale inhibitors.

Index Terms—Polyepoxysuccinic acid, calcium phosphate,

hydroxyapatite, molecular dynamics simulation, static

scale-inhibiting method, crystal surface.

I. INTRODUCTION

An impressive set of researches on the precipitation of

calcium phosphate have been performed by many researchers

[1]-[4]. This is because the importance of calcium phosphate

precipitation in diverse areas including pathological

biomineral deposits resulting in problems (e.g., dental

calculus, arteriosclerosis, urinary calculi, etc.), oil and gas

production, water purification, energy production technology,

waste water treatment processes and industrial water systems,

where calcium phosphate precipitation on heat exchanger

surfaces could result in decreased efficiency of the system and

explosion accidents.

Adding scale inhibitors to the system is the specially

common and effective way to prevent the deposition of

calcium phosphate. Hydroxyapatite (HAP) is the most

thermodynamically stable among different calcium phosphate

phases [5], [6]. The growth of HAP could be prevented or

slowed with the use of scale inhibitors; in addition, the crystal

morphology of HAP could be changed due to the influence of

Manuscript received February 6, 2014; revised June 8, 2014.

Wu Lei and Gang Chen are with the Department of Chemistry, Nanjing

University of Science and Technology, Nanjing, China (e-mail:

leiwuhao@yahoo.com.cn, 691400451@qq.com).

Wenyan Shi is with the Department of Applied Chemistry, Yancheng

Institute of Technology, Yancheng, China (e-mail: waterswy@126.com).

scale inhibitors. Up to now, the research, development and

performance evaluation of new scale inhibitors still mainly

rely on experimental and experience extrapolation methods,

which will be prone to bring on the waste of time, manpower

and material resources. However, the experimental results

could not provide us enough microscopic details about how

the scale inhibitors interact with the inorganic scale crystal,

and the interaction mechanism is still not clear. In contrast,

molecular dynamics (MD) simulation can be used to obtain

more detailed insights into the scale inhibition mechanism and

the effect of scale inhibitors on the morphology of inorganic

scale crystal [7]-[9].

Polyepoxysuccinic acid (PESA) is an environment-friendly

scale inhibitor synthesized at the beginning of 1990s by

Prector & Gamble Company and Betz Company, respectively

[10]. PESA is a kind of organic compound which is

biodegradable and does not contain nitrogen and phosphorus.

According to the characteristics of PESA, such as excellent

thermal stability, less amount used and synergistic effect for

corrosion inhibition, it is being an important study problem in

water treatment field. In China, the synthesis and scale

inhibition performance of PESA have been researched since

late 1990s, the results indicate that PESA is very capable of

controlling calcium carbonate, calcium sulfate and barium

sulfate. However, very little is known about the antiscaling

property and scale inhibition mechanism of PESA for calcium

phosphate scales.

For this purpose, in the present work, the scale inhibition

performance of PESA on the precipitation of calcium

phosphate was studied by static scale-inhibiting method to

explore the effect of scale inhibitor concentration on the scale

inhibition performance, and scanning electron microscopy

(SEM) was employed to characterize the morphology of HAP

to elucidate the role of PESA in the process of crystal growth.

On the other hand, the PESA adsorption on the main growth

crystal surfaces of HAP in aqueous solution was investigated

using Molecular dynamics (MD) simulation to find out the

essence of the interaction and the scale inhibition mechanism

of PESA. The results provide theoretical guidance to practical

applications of PESA.

II. EXPERIMENT

A. Materials

PESA was provided by Changzhou Wujin Water Quality

Stabilizer Factory (Jiangsu, China) and was industrial product.

Anhydrous calcium chloride, potassium dihydrogen

phosphate and sodium tetraborate decahydrate were all

analytical reagent grade chemicals.

The Scale Inhibition Performance and Mechanism of

Polyepoxysuccinic Acid for Calcium Phosphate

Wu Lei, Wenyan Shi, and Gang Chen

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

184DOI: 10.7763/IJCEA.2015.V6.478

B. Static Scale-Inhibiting Method

The static scale-inhibiting method was used to determine

the scale inhibition efficiency over a range of concentrations

(mg/L) for PESA. Briefly this was as follows:

A simulated water sample containing 250 mg/L (calculated

by CaCO3 concentration) calcium ion and 5 mg/L(calculated

by PO43-

concentration) phosphate was obtained with

anhydrous calcium chloride and potassium dihydrogen

phosphate, and the pH of the solution was brought to the

desired value 9.0 by the careful slow addition of sodium

tetraborate decahydrate solution. The scale inhibitor was

added to the simulated water sample, and the solution was

heated 10 hours at 80℃. After this stage was completed, the solution was cooled and then filtered. Finally, the

concentration of phosphate in the filtrate was measured with

spectrophotometry. The scale inhibition efficiency (η) was

computed according to the following equation:

η = (c1 - c0) /( cb - c0 ) ×100%=(I1-I0)/( Ib-I0) ×100% (1)

where cb (Ib) is the concentration (absorbance) of PO43-

in the

simulated water sample(without heating), mg/L, c0 (I0) and c1

(I1) are the concentration (absorbance) of PO43-

in the filtrate,

absence and in the presence of inhibitor, respectively, mg/L.

C. Molecular Dynamics Simulation Method

1) Simulation force field

COMPASS force field [11], available from molecular

modeling program Materials Studio 3.0 [12] from Accelrys

Software Inc. (USA), was used to simulate the interaction of

PESA with HAP crystal surfaces. On the one hand, it is the

first ab initio force field which has been parameterized and

validated using condensed phase properties, in addition to

various ab initio and empirical data for molecules in isolation.

Consequently, this force field enables the accurate and

simultaneous prediction of structural, conformational,

vibrational, and thermophysical properties for a broad range

of molecules in isolation or condensed phases under a wide

range of conditions of temperature and pressure. On the other

hand, this force field has been successfully employed to

investigate the carboxylic polymers [1], [7]. The detailed

expressions used to represent the energy surface of

COMPASS force field were shown in literatures [11]-[14].

2) Model construction

The models were built with Visualizer module, molecular

dynamics (MD) and the energy minimization (EM)

calculations were performed on Discover module.

Hydroxyapatite crystals belong to the P63/m space group

[15], hexagonal crystal system; the lattice parameters are as

follows: a = b = 0.9424 nm, c = 0.6879 nm, α = β = 90°, γ =

120°. The mode which the surface cells are created from the

unit cell of HAP at its cleavage planes was adopted to

research the effect of PESA dissolved in water on the growth

of (001) and (010) crystal surfaces. The super cells of surface

(001) and (010) were extended to 3D periodic super cells of

2.752 nm × 3.264 nm × 3.463 nm and 2.752 nm × 2.827 nm ×

3.888 nm, respectively. Because it is out of the capability of

the current simulation technique to take all of these factors

into account simultaneously, these variables were changed

step by step. In the present work, the HAP crystal surfaces

considered were perfect planes, without defects such as

vacancies, steps or kink sites.

The degree of polymerization of PESA was set to 20. The

alkyl chains of the polymers are flexible, free to bend and

rotate. Therefore, polymers have a variety of configurations,

which were continuously converted mutually. Aside from the

lowest energy configuration, there were considerable higher

energy configurations; however, It was unrealistic to take

over all of the possible configurations. With this in mind, the

deviation was reduced by increasing the number of

configurations, making the simulation results closer to the

actual. The torsion angles between the monomers were set to

0°, ±45°, ±90°, ±135°and 180°; for each torsion angle, ten

configurations were randomly constructed as a set of samples,

then eight sets of samples were constructed, specifically,

eighty configurations in total for PESA. All the MD

simulations of these eighty configurations were carried out at

353 K in the NVT ensemble [16]. MD simulation time was

100 ps and the time step was set to 1 fs; every 5000 steps

generated one outcome and 20 frames were generated in total.

The configuration of the twentieth frame was optimized to

determine the minimum energy using a molecular mechanic

(MM) method, the smart minimizer, which combines the

steepest descent algorithm, the conjugate gradient algorithm,

and the Newton algorithm. The ten lowest energy

conformations of the eighty configurations reform a set of

samples.

A “liquid layer” consisted of one PESA molecule and two

hundred water molecules was added to the simulation box in

close proximity to the (001) and (010) surfaces of HAP as

starting state. As to the two hundred water molecules, they all

moved freely within periodic system boundary. The thickness

of vacuum slab along the Z-axis (c) direction was 2.0 nm.

All MD simulations were carried out in the NVT ensemble

[16]. The coupling to the heating bath was carried out using

the Berendsen method [17], with a relaxation time of 0.1 ps.

MD simulation was started by taking initial velocities from a

Maxwell distribution. The solution to Newton’s Laws of

Motion was based on assumptions as follows: periodic

boundary condition, and time average equivalent to the

ensemble average. Integral summation was carried out with a

Verlet velocity integrator [18]. The nonbonding interactions

in each system, as well as the Van der Waals force and

electrostatic force were computed using an atom-based

summation method and the Ewald summation method,

respectively, with a cutoff radius of 0.95 nm (spline width:

0.10 nm; buffer width: 0.05 nm). When any interaction pair

moves more than half this distance, the neighbor list is

recreated. Tail corrections were used to calculate the potential

energy contributions from interactions between atoms

separated by distances longer than the nonbonding cutoff.

Annealing was done using a self-compiled program and the

initial temperature of the simulated annealing algorithm was

set to 953 K, the temperature deceased once every 50 K, and

the MD simulations were performed at each temperature point,

till the end temperature 353 K (80°C), which was the actual

application temperature of the scale inhibitors. The time step

was set to 1 fs, equilibration stage ran for 100000 fs, and then

the production stage also ran for 200000 fs, the data were

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

185

collected for subsequent analysis at the same time. The

trajectory was recorded every 500 fs.

3) Solvent effect

As the scale inhibitor discussed is used in cooling water

circulation system, therefore it is very important to consider

the solvent effect on the simulation results. An aqueous

environment was included through the explicit inclusion of

water molecules in the simulations. In order to model a more

realistic system, the whole simulation box included the HAP

crystal surface, the “liquid layer” and an additional layer of

five hundred water molecules with fixed spatial positions,

acting as the water bulk but with the same physical and

chemical properties [19]. The schematic view of the starting

conformations for H2O/PESA/HAP surface supramolecular

system is shown in Fig. 1.

a. H2O/PESA/HAP (001) surface b. H2O/PESA/HAP (010) surface

Fig. 1. The starting conformations of H2O/PESA/HAP surface

supramolecular systems.

III. RESULTS AND DISCUSSIONS

A. Effect of the Concentration of PESA on Scale Inhibition

Efficiency

The scale inhibition performance of PESA on calcium

phosphate scale has been evaluated using the static

scale-inhibiting method and was compared with that of

commonly used scale inhibitors, such as polyacrylic acid

(PAA) and a copolymer of phosphorous acid/acrylic

acid/1-acrylanmido-2-methylpropanesulfonic acid (POCA).

The scale inhibition efficiency of PESA, PAA and POCA for

Ca3 (PO4)2 with different concentrations is shown in Table I.

TABLE I: SCALE INHIBITION EFFICIENCY OF PESA, PAA AND POCA FOR

CA3 (PO4)2

samples

Scale inhibiting efficiency (%) with different concentrations

(mg/L)

5 10 15 20 25 30 35 40

PESA 7.0 31.2 37.3 45 52.8 65.5 74.6 80.4

PAA 10.0 16.6 19.7 21.3 28.9 30.1 30.7 30.9

POCA 25.4 43.7 49.1 94.4 100 100 100 100

Analysis of Table I indicates that the scale inhibition

efficiency of PESA increases as the increase in the

concentration. PESA demonstrates poor anti-scale efficiency

for calcium phosphate scale at low scale inhibitor

concentration, however exhibits better performance at high

concentration. PESA shows better scale inhibition

performance compared with PAA while poor performance

compared with POCA, this is because POCA contains

sulfonic group and hydroxyl group which is beneficial to the

scale inhibition efficiency for calcium phosphate scale.

The growth processes of calcium phosphate scale was

examined using scanning electron microscopy(SEM), in

order to explore the effect of PESA on the growth

morphology of HAP crystal and the scale inhibition

mechanism of PESA, as shown in Fig. 2.

a. Scale without PESA

b. Scale with 10mg/L PESA

Fig. 2. The crystal morphology of PESA recorded by SEM.

From the analysis of Fig. 2, it can be known that the shape

of HAP was more regular and the particle size was larger,

which manifests that the calcium phosphate scale grows

quickly. However, adding PESA (10mg/L) to the simulated

water sample, the scale became smaller compared with the

scale without PESA, which indicates that PESA possesses

better dispersing property, making the scale stay in the

microcrystal state. Moreover, the shape of HAP is not regular

and the scale crystal structure is not obvious, which shows

that PESA can adsorb on the crystal surfaces, interact with the

surfaces and lead to distortion of crystal lattice. In this paper,

the interaction between PESA and the main growth crystal

surfaces of HAP was simulated with MD method, intending to

investigate the scale inhibition mechanism of PESA for

calcium phosphate.

B. Equilibrium Criteria of Interaction between PESA and

HAP Crystal Surfaces

The system must reach the equilibrium state before the

production runs and the equilibrium of the system can be

judged using the equilibrium criteria for temperature and

energy [20], that is, when the fluctuations of temperature and

energy are in the range of 5%-10%, the equilibrium of the

system is ascertained. For the last 15ps during the

equilibration period of PESA on the (010) surface of HAP

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

186

crystal, the temperature fluctuated between 325K and 377K,

which indicates that the temperature reached the equilibrium

state because the temperature fluctuated in the setting

temperature 353±28 K and the statistical fluctuation of

temperature has met the requirement of the temperature

criteria. The energy fluctuation curve in the MD simulation of

PESA on the (010) surface of HAP crystal for the last 15ps

during the equilibration period are shown in Fig. 3.

0 10 20 30 40 50 60 70 80 90 100

1434

1436

1438

1440

1442

1444

1446

1448

En

erg

y/e

V

Time/ps Fig. 3. The energy fluctuation curve of the binding process of PESA on the

(010) surface of HAP.

As shown in Fig. 3, The energy fluctuation curve is in the

range of 0.2%-0.3% during the equilibration period of PESA

and the (010) surface of HAP crystal, which indicates that

simulation system has reached energy equilibration state and

the analytical results of the production runs are reliable.

Similar conclusions were obtained when analyzing the system

composed of PESA molecule and the (001) surface of HAP.

C. Binding Energy of PESA Absorbed on HAP Crystal

Surfaces

Binding energy (E b) can well describe the intermolecular

interaction strength between the scale inhibitors and the scale

crystal, which is defined as the negative value of the

interaction energy (E inter). E inter can be evaluated by the total

energy of the supramolecular system and its corresponding

components in the equilibrium state. Therefore, E b between

PESA and HAP crystal surface in aqueous solution can be

calculated by the following expression: [21], [22]

E b = -E inter = ET – EPESA+water – Esurf+water +Ewater (2)

where ET is the total energy of H2O/PESA/HAP

supramolecular system, EPESA+water and Esurf+water are the total

energies of the system containing only PESA and water, the

HAP crystal surface and water respectively, Ewater is the total

energy of water.

As shown in Fig. 4, PESA molecules adsorbed closely on

the HAP crystal surfaces in presence of water after MD

simulation, consequently extensive interactions existed

between PESA and HAP crystal surfaces and the

configurations of PESA were deformed in the process of

interaction. The deformation degree of the structure of a

molecule is evaluated by deformation energy (E d).

E d =E poly-b – E poly (3)

E poly-b and E poly are single point energy of the polymer

molecule being absorbed and being in free status,

respectively.

a. (001)surface b. (010)surface

Fig. 4. Equilibrium structures of PESA adsorbing on (001) and (010)

crystal surfaces of HAP.

For visualization, average total energies (ET) of the

supramolecular system, single point energies of the

constituent parts (EPESA+water, Esurf+water and Ewater),

interaction energies (E inter), binding energies (E b) and the

corresponding deformation energies (E d) of PESA are

presented in Table II (unit: eV).

TABLE II: BINDING ENERGIES BETWEEN PESA AND HAP CRYSTAL SURFACES AND THE CORRESPONDING DEFORMATION ENERGIES OF PESA (EV)

surface ET E PESA+water E surf+water E water E inter E b E poly-b E poly E d

(001) 96974.6 -574.6 97785.8 -324.1 -560.7 560.7 24.4 20.1 4.3

(010) 111633.8 -600.87 112568.6 -675.0 -1008.9 1008.9 25.0 15.6 9.4

As shown in Table II, the interaction energies of both

PESA-HAP (001) and PESA-HAP (010) supramolecular

systems are negative, which indicates that the combination of

PESA with HAP crystal surfaces is exothermic and

thermodynamically favourable, in agreement with the

illustration of Fig. 4. The more binding energy is, the strong

the intermolecular interaction is. The binding energy of PESA

with HAP (010) surface is 1.8 times larger than that of PESA

with HAP (001) surface, which manifests that the growth of

HAP (010) surface was dramatically inhibited by PESA

compared with that of HAP (001) surface, leading to changes

in the crystal morphology of HAP. The structures of PESA

adsorbed on HAP (001) and (010) surfaces are both distorted

strongly.

D. Radial Distribution Function of the Supramolecular

System

The radial distribution function g(r) is usually used to

describe the degree of atom disorder in the molecule and can

give a measure of the probability of finding a pair of atoms at

a given distance (r) in a random distribution. The radial

distribution function has found applications in structural

investigations of both solid and liquid packing, in studying

specific interactions such as hydrogen bonding. The g(r) of

the superamolecular system is obtained through analyzing the

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

187

MD simulation result of PESA with HAP crystal surface. Take

the PESA-HAP (010) superamolecular system as an

illustration, the radial distribution function of oxygen atoms,

hydrogen atoms in PESA with calcium ions, oxygen atoms in

HAP (010) surface are shown in Fig. 5, respectively. Similar

g(r) graphs can be obtained when analyzing PESA-HAP (001)

superamolecular system.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

g(r

)

r/nm

g(r)O-Ca

g(r)H-O

Fig. 5. Radial distribution function of PESA and HAP (010) surface.

Generally, in g(r)~r graph, the peak which is within 0.35nm

mainly consists of chemical bond and hydrogen bond，while

the peak which is outside of 0.35nm is mainly composed of

the Coulomb and van der Waals forces. As shown in Fig. 5,

the first peak of g(r)O-Ca curve appears around 0.275 nm,

which is larger than O-Ca electrovalent bond length, 0.239 nm.

This indicates that electrovalent bond cannot be formed

between oxygen atoms and calcium ions but strong Coulomb

forces exist. Analyzing the g(r)H-O curve , there is a sharp peak

in r=0.207 nm, and it means that the strong hydrogen bonds

exist between hydrogen atoms in PESA and oxygen atoms in

HAP (010) surface.

IV. CONCLUSION

In this paper, the scale inhibition performance of PESA for

calcium phosphate was evaluated by static scale-inhibiting

method and the interaction of PESA with HAP was

investigated by means of MD simulations and scanning

electron microscopy(SEM). The major results can be

summarized as follows.

1) PESA exhibits better performance for calcium phosphate

scale at high scale inhibitor concentration while poor

anti-scale efficiency at low concentration and shows

better scale inhibition performance compared with PAA

while poor performance compared with POCA.

2) PESA possesses better dispersing property and leads to

the distortion of HAP crystal lattice.

3) PESA molecules adsorb on the surfaces rather than

remain in the bulk water in MD simulations and the

binding energy of PESA with (010) is significantly

stronger (1.8 times) than that with (001) surface, which is

mainly provided by hydrogen bonds and coulomb

interaction verified by analysis of the radial distribution

function. The adsorption of PESA molecules change the

growth rate of crystal surfaces and lead to changes in the

crystal morphology of HAP, according well with

scanning electron microscopy (SEM) results.

REFERENCES

[1] S. G. Zhang, F. Y. Wang, and X. Y. Tan, “Molecular dynamics

simulation on the hydroxyapatite scale inhibition mechanism of

water-soluble polymers,” Journal of Theoretical & Computational

Chemistry, vol. 5, pp. 889-902, 2010.

[2] C. Y. Chen, M. Z. Xia, L. Wu, C. Zhou, and F. Y. Wang, “Modeling

the interaction of seven bisphosphonates with the hydroxyapatite (100)

face,” J. Mol. Model., vol. 18, pp. 4007-4012, 2012.

[3] N. H. de Leeuw, “Computer simulations of structures and properties of

the biomaterial hydroxylapatite,” Journal of Materials Chemistry, vol.

26, pp. 5376-5389, 2010.

[4] A. Tsortos and G. H. Nancollas, “The role of polycarboxylic acids in

calcium phosphate mineralization,” Journal of Colloid and Interface

Science, vol. 250, pp. 159-167, 2002.

[5] N. H. de Leeuw and J. A. L. Rabone, “Molecular dynamics simulations

of the interaction of citric acid with the hydroxyapatite (0001) and

(01-10) surfaces in an aqueous environment,” Cryst Eng Commum, vol.

9, pp. 1178-1186, 2007.

[6] S. Koutsopoulos, “Kinetic study on the crystal growth of

hydroxyapatite,” Langmuir, vol. 17, pp. 8092-8097, 2001.

[7] Q. Y. Zhang, H. Ren, W.W. Wang, J. P. Zhang, and H. P. Zhang,

“Molecular simulation of oligomer inhibitors for calcite scale,”

Particuology, vol. 10, pp. 266-275, 2012.

[8] C. Schmidt and J. UIrich, “Crystal habit prediction-including the

liquid as well as the solid side,” Cryst. Res. Technol., vol. 6, pp.

597-602, 2012.

[9] A. Fiebig, M. J. Jones, and J. Ulrich, “Predicting the effect of impurity

adsorption on crystal morphology,” Crystal Growth & Design, vol. 9,

pp. 1623-1627, 2007.

[10] J. M. Brown and J. F. Mc Dowell, “Method of controlling scale

formation in aqueous systems,” U.S. Patent 5147555, 1992.

[11] H. J. Sun, “Compass: An ab initio force field optimized for condensed

phase application, overview with detail on alkane and benzene

compouds,” J. Phys. Chem. B., vol. 102, pp. 7338-7364, 1998.

[12] Materials Studio 3.0, Discover/Accelrys Software Inc., San Diego,

California, 2004.

[13] H. Sun, P. Ren, and J. R. Fried, “The compass force field:

Parameterization and validation for phosphazenes,” Comput. Theor.

Polym. Sci., vol. 8, issue 1-2, pp. 229-246, 1998.

[14] D. Rigby, H. Sun, and B. E. Eichinger, “Computer simulations of poly

(ethylene oxide): Force field, pvt diagram and cyclization behaviour,”

Polymer International, vol. 44, pp. 311-330, 1998.

[15] A.Wierzbicki and H. S. Cheung, “Molecular modeling of inhibition of

hydroxyapatite by phosphocitrate,” Journal of Molecular Structure:

THEOCHEM, vol. 529, no. 1, pp. 73-82, 2000.

[16] D. W. Heermann, Computer Simulation Methods in the Theoretical

Physics, Beijing: Peking University Press, 1996, pp. 89-102.

[17] H. J. C. Berendsen, J. P. M. Postma, and W. F. J. van Gunsteren,

“Molecular dynamics with coupling to an external bath,” Chemical

Physics, vol. 81, pp. 3684-3690, 1984.

[18] M. P. Allen and D. J. Tildesley, Computer Simulation of Liquids,

Oxford: Clarendon Press, 1987, pp. 56-67.

[19] J. P. Zhang, Q. Y. Zhang, H. Ren, W. Zhao, and H. P. Zhang,

“Inhibition performance of 2-mercaptobenzothiazole derivatives in

CO2 saturated solution and its adsorption behavior at Fe surface,”

Applied Surface Science, vol. 253, pp. 7416-7422, 2007.

[20] D. Frenkel and B. Smit, Molecular Simulation−From Algorithms to

Applications, Beijing: Chemical Industry Press, 2002, pp. 34-57.

[21] M. J. Yang, S. L. S. Stipp, and J. Harding, “Biological control on

calcite crystallization by polysaccharides,” Crystal Growth & Design,

vol. 11, pp. 4066-4074, 2008.

[22] B. Rai and P. Sathish, “Rational design of dispersants by molecular

modeling for advanced ceramics processing applications,” KONA, vol.

22, pp. 151-158, 2004.

Gang Chen was born in 1987, who is studying Ph.D. of

materials science and engineering specialty at Institute

of Industrial Chemistry of Nanjing University of

Science and Technology.

His research interests include research on the

technique of industrial water treatment and theoretical

study of energetic materials.

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

188

http://apps.webofknowledge.com/OneClickSearch.do?product=UA&search_mode=OneClickSearch&colName=WOS&SID=Y241KaDN84PonLagKIE&field=AU&value=de%20Leeuw,%20NH&ut=10925507&pos=%7b2%7d

Wenyan Shi was born in Hengshui, Hebei, P.R. China

on June 2, 1980. Ms. Shi earned his B.S. degree of

chemical education from Hebei Normal University in

2003, the M.S. of physical chemistry from Nanjing

University of Science & Technology in 2005.

Now she works as a teacher in Yancheng Institute of

Science and Technology. She has been engaged in

researching the relationship between structure and

function of the organic compounds containing phosphor and of low

polymers for more than 10 years. There are more than 15 papers which have

already been published

Wu Lei was born in Wuhan, Hubei, P.R. China, on

October 26, 1971. Mr Lei earned his B.S. degree of

chemical engineering from Nanjing University of

Chemical Engineering in 1993, the M.S. of physical

chemistry and Ph.D. degree of applied chemistry from

Nanjing University of Science & Technology.

He works as a researcher in Water Treatment

Institute (now named Institute of Industrial Chemistry) in College of

Chemical Engineering of Nanjing University of Science & Technology. He

has been engaged in researching in the fields of synthesis, analysis and

application of new water treatment agents; the engineering design of water

treatment projects and the analysis of water quality; sensors for

environmental protection. As a main researcher, he has already taken on the

research work of many projects from enterprises and the government of state

departments and provinces up to now. There are 22 papers and 1 patent

which have already been published and can be retrieved by international

searching system or center.

International Journal of Chemical Engineering and Applications, Vol. 6, No. 3, June 2015

189